/Engine/Source/Runtime/Core/Public/Async/Fundamental/Task.h
namespace LowLevelTasks { enum ETaskFlags { AllowNothing = 0 << 0, AllowBusyWaiting = 1 << 0, AllowCancellation = 1 << 1, AllowEverything = AllowBusyWaiting | AllowCancellation, DefaultFlags = AllowEverything, } }